Process and apparatus for fractionating hydrocarbon oils



Nov. 20, 1928.

J. C. BLACK PROCESS AND APPARATUS FOR FRACTIOATING HYDROCARBON OILS ITB 25% Filed Feb. 2, 1924 Patented Nov. 20, 192s.

NITED STATES JOHN C. BLACK, OF DESTREHAN, LOUISIANA. A

PRQCESS AND APARATUS FOR FRACTIONATING HYDROCABBON OILS.

Application led February 2, 1924. Serial No. 690,207.

This invention relates to a process and apparatus for ractionating hydrocarbon oils and more particularly to the fractionation or separation of hydrocarbons of various boiling points from a vapor in which they are commingled.

This invention is a continuation in part of my previous application, Serial No. 630,1497, filed April 5, 1923, and is carried out along somewhat similar lines, but embodies improvementsthat simplify the apparatus, reduce labor of handling and economize heat for evaporation. l

In my present invention I. employ two towers, or fractionating columns, as I prefer to split the operation into two stages. More towers may be used if closer fractionation is desired, but two towers, as illustrated in the drawing, will clearly show the process and will avoid multiplicity-of detail.

This process is particularly'well adapted to the production of gasoline from crude oil or crude naphtha and when operating on crude oil it will produce a test gasoline in one operation, without the necessity of first making a crude naphtha which requires subsequent steam distillation as in the old method of operating with the attendant double handling, double gas loss and greater heat consumption for vaporization.

By this'method of operation I am enabled to obtain an increased yield of the desirable gasoline fraction of specific boiling points and to obtain a residual product from the steam still substantially free of gasoline boiling point fraction and if so desired, the elimina-` tion of all intermediate fraction between gasoline and steam still residue.

ln this apparatus l am enabled to introduce hydrocarbons of specific boiling points, blending them in the vapor form to produce a homogeneous mixture and producing in the final condensation product a inished oil having certain specied'boiling points as, for instance, ithe natural product wasvdecient in the amount distilled at 212 F. a hydrocarbon whose boiling point would be below 212 F. may be introduced into the fractionating apparatus from an outside source and may be so introduced that it will be vaporized and a homogeneous blend made with the mass of vapors undergoing fractionation, and will ass to the main condenser, producing there- 1n a condensate which o'n distillation will show the proper or specified amount distilling at 212 F. Likewise, an y deficiency in the natural boiling pointY ran e of the iinished condensate may be alteredy the addition of an outside source of Vhydrocarbons having boiling points capable of correcting the deciency.

The apparatus also provides for the extrae tion bf intermediate condensates, if so desired; that is, if the final condensation product has an overabundance of hydrocarbons of certain boiling points, then by roper mani ulation of the apparatus the undbsirable hydio car-bons may be eliminated from the vapors passing to the condenser and the finished or final condensate will then meet the required specification as far as that particular fraction is concerned.

The accompanying drawings show in one figure the apparatus in `part section and part elevation and anyone familiar with the art to which the invention applies will readily understand its operation and construction.

For convenience, I show the apparatus conneeted to a single still although it may be applied to a battery of'stills of the continuous type and the piping can be so arranged that the intermediate condensates may be passed for revaporization to other stills of the series. Likewise the crude oil may be passed through a battery of stills in accordance with the conventional manner of operating such stills. Also the crude oil or the distillates used to cool the top condensers may be introduced into the stills at any point desired or otherwise disposed of, as for instance, cooling it and recirculating it. This, however, is inmaterial to the process and isv well-known in the art.

Referring to the drawin Y, 1 is the still or source of the vapors to be ractionated. 2 is the vapor line connecting the still to the first tower or fraetionating column 3. 4 is a separating chamber having a tight bottom 5 and a hooded top opening 6; it also has a runback line 6l connected to a trap 62, the combination acting as a conduit between chamber 4 and the still l.. 7 shows the baffling material in the tower 3 which may be tile, stone or other material or may be baffle plates or trays. 8 is a vapor condenser and heat exchanger fitted with tubes 9 designed to carry the cooling medium introduced through line 56 and valve 56. 10 is a vapor pipe connectingI the condenser 8 to the second tower 11. This tower is referably itted with boiling decks and iling caps 12 of the well known type. 13 is a condenser fittedwith tubes 14 supplied with a cooling medium through pipe 55 and valvel 55. 15 is a vapor pipe connected to a condenser 16 which in turn connects with the look boX 17, and pipe 18 to the finished oil tank. 19 is a gas vent connected to the gas main 20. 21 is the lower portion of the tower 3 and is constructed so as to act as a steam still. This may be a lseparate structure, but I prefer to build it as shown, the upper portion of the still being fitted with boiling decks and boiling caps 22 similar to 12. These may be eliminated if so desired without materially affecting the process. 23 is a vapor pipe connecting the still 21 to the still 24 A which is similar to still 21 and is fitted with boiling decks and boiling caps 32. These, however, are not necessarily essential, but I prefer them, as improved fractionation 1s obtained thereby. Still 24 is fitted w1th a top hooded opening 33 which will permit the' vapor generated in still 21 and 24 to pass into the tower 11. 25 is a drain pipe fitted with a trap 25 and connects the lower portion of the tower 3 just above the separating chamber with the steam still 21. 26 is a drain line for the still 21 and is connected to pipe 27 and valve 27 to the cooler 28 and through pipe 29 to tank 30. Tank 30 is fitted with a pipe 31 and valve 31 for removing the accumulation of oil. This tank is also fitted with suction pipe 50 and valve 50 to pump 49 on its suction side. 34 is a drain pipe fitted with a valve 34 and a tra 34". This pipe has a connection 35 and va ve 35 into the still 24. It also has a bypass connection 36 and valve 36 connected to the cooler 37 which in turn is connected through pipe 38 to tank 39. Tank39 is provided with a pipe 40 and valve 40 to permit removing accumulation of oil. It isalso provided with a pipe 41 and valve 41 to the suction side of the pump 49 through the pipe 49. Pipe 41 may however connect direct to the pump 49 without the intermediary of pipe 49". Pipe 34 connects with the suction side of pump 49 through the pipe 49. Pipe 34 may however connect direct to the pump 49 without the intermediary of pipe 49. 42l is a drain pipe for the still 24 and is connected thru pipe 43 and valve 43 to the cooler 44 which in turn is connected thru pipe 45 to tank 46. Tank 46 is fitted with pipe 47 and valve 47 to permit removal of accumulation of oil. 4It is also fitted with pipe 48 and valve 48 to the pump 49 through pipe 49. Pipe 48 may connect direct to the pump 49 without the intermediary of pipe '49. The pump 49 islalsofitted on its suction side with a pipe 68 and valve 68 which in turn is connected'to any outside source of oil not shown on the drawing. The pump 49 is fitted on its discharge side with a pipe 51. This pipe is arranged to discharge through valve lfyfyinto the spray pipe`52 in tower 3 and it is also fitted with a branch connection 53 and valve 53 into tower 11. Branching from discharge pipe 51 there is a pipe connection 69 with valve 69 connecting with the still 1. 54 is a pipe designed to carry the cooling medium to the condensers 8 and 13 through the pipes 55 and valve 55 and pipe 56 and valve 56. 57 is a cross connection between the two condensers 8 and 13 so arranged as to permit the partially heated cooling medium leaving the tubes 14 to pass over into the tubes 9. Pipe 57 is fitted with a valve 57. 57 is also provided with a bypass pipe 58 and valve 58 to permit the cooling medium leaving tubes 14 to pass directly to the pipe 60. The condenser 8 is fitted with a discharge pipe 59 and valve 59 to permit the .cooling medium leaving tubes 9 to discharge into pipe 60. Pipe 60 is a manifold connection connecting the still 1 through valve 60 to the discharge pipes 58 and 59 and to pipe 54 through valve 54. -60 is also provided with a bypass pipe 7 0 and valve 70 to permit of disposal of the cooling medium other than into the still 1, as for instance, into .a cooler from which it could be recirculated to be again used as a cooling medium. 61 is' a runback pipe fitted with a trap 62. This pipe connects the separating chamber 4 with the still 1 and is designed to conduct any condensation products occurring in 4 back to the still 1. 63 is a steam line from which are branches 64 and valve 64 and 65 and valve 65. These two pipes discharge open steam into the steam stills 21 and 24. There is a similar connection 66 and valve 66 and 67 and valve 67 which supply closed steam to the stills 21 and 24.

Having now described my apparatus I will describe the process of fractionation as carried on therein.

If I am distilling crude oil for the production of gasoline I will charge the crude into the still 1 through the pipe 54, valve 54', pipe 60 and valve 60. or any other suitable means, as for instance, in a continuous battery of stills the crude may be introduced into the stills in the usual manner employed in that process. The crude oil is then heated in the usual manner and the vapor is conducted through the pipe y2 into the separating chamber 4. If any entrained crude or condensation products collect in this chamber they are conducted back to the 'still 1 through the pipe 61 to be again subjected to distillation. The vapor leaves chamber 4 through the hooded opening 6 and passes up through the bafiiing material 7. The vapor then passes into the condenser 8 and out through vaporpipe 10 to the inlet of tower 11 then passes up through the boiling decks 12 to the condenser 13 and out through vapor pipe 15 to the condenser 16, look box 17 and pipe 18 to the finished oil tank. This is the generalkffow of the vapor,

but in passing up through tower 3 it meets lll a down-coming condensate sprayed through 52. This spray pipe is fed through pipe 51 connected to the discharge of pump 49. This pump taking its supply preferably from the bottom of tower l1 through pipe 34. This condensate is a light intermediate and is the reflux .descending from the boiling decks 12 and contains a substantial quantity of desirable fractions belonging in the final condensate condensed in 16. This reflux is pumped hot into the tower 3 where it meets the ascending hot vapors and steam from the still 1 and the light portions thereof are distilled out and join with the vapor passing At0 tower 11, thereby enriching those vapors with light products. This distillation of the light products of the reflux will absorb heat of vaporization from the vapors in tower 3 and as a result a certain amount of vapor willv be cooled below its vaporization point and will be precipitated to the lower portion of tower 3. The above described action 'is also increased by the cooling and condensing action of the reflux due to its cooler and liquid condition. It is also increased by the reflux obtained from the condenser 8, the temperature of which is also regulated as to condense the heavier or high boiling point hydrocarbons. In this manner the vapor passing out through pipe 10 contains an appreciably increased percentage of low boiling hydrocarbons over that originally contained in the vapors issuing from still 1. If through any cause I could not circulate the hot reflux coming from tower 11 I can store it in tank 39 by passing it through pipe 36, valve 36 and .cooler 37 and pipe 38 or I may bypass it through pipe 35 and valve 35 into the steam still 24 where the light or low boiling point fractions may be distilled out by the use of steam the vapors so produced ascending through the hooded opening 33 into the tower 11 there to join the vapors entering 11 through pipe 10. The residue in still 24 may be discharged through pipe 42, pipe 43 and valve 43 into the cooler 44, pipe 45 into tank 46. This ystock I. denominate heavy intermediatel and that in tank 39 light intermediate.

From these two tanks 39 and 46 pipe connection is made to the pump 49 so that these stocks may be pumped into tower 3 there to be relieved of their low boiling fractions and eliminate the accumulation of intermediates. The heavy ends or high boiling fractions not so evaporated will pass down through tower 3 out through drain pipe 25 and trap 25 into the steam still 21 where if by any chance any light or low boiling fractions still remain they will bev evaporated in the still by introduction of steam and heat supplied through steam connections 64 and 66. The vapors so produced pass over into still 24 through vapor pipe 23 thencev through hooded opening 33 into tower 11. There is provided a connection 53 with valve 53 from pipe 51 discharging into tower 11. This is to provide an artificial reflux so to speak, to augment the natural reflux obtained from the boiling decks 12 and condenser 13. This may be used in starting up or if the vapors are coming over too fast, this artificial reflux will offer a dampening eEect on the vapors and make for steadier operation of 'the plant. Thus it will be seen that the vapors passing into tower 11 are largely freed of their high boiling point hydrocarbonsl and enriched with low'boiling point hydrocarbons. The vapors now pass up through lthe boiling decks 12 where further separation of high boiling point fractions are made. These fractions however will remove along with the high boiling point fractions considerable of the lower boiling point fractions and will make what I denominate a light intermediate and it is this fraction in conjunction with any condensate made in condenser 13 that is sprayed into tower 3 through spray pipe 52 there to besubjected to revaporization and separation of the low from the high boiling point fractions as previously described.

In this type of equipment the first `tower l acts as a preliminary vfractionator and produces a residual vapor containing certain percentages of high boiling fractions which pass into the second tower and are therein fractionated to a high degree, whereby the undesired high boiling fractions are completely separated from the residual vapors. The'residual vapors from this second fractionating tower pass through a condenser, where the same are condensed and collected. By this method of employing two fractionating towers in the series, an increased yield is obtained of these hydrocarbons, vhaving a specified boiling point range.

As hereinbefore stated the composition of the residual vapors may be varied through a -wide range (that is the condensate will contain fractions that can be varied through a wide range) by adding hydrocarbons of specific boiling points and which may be introduced into the system through pipe 68 and valve 68 as previously described. On the other hand, if certain fractions predominate they may be reduced by condensation from the vapors in one tower or the other and removed from the system, as for instance by passing some of the reflux from tower 11 into the light intermediate tank 39 and removing it from the system through pipe 40 and valve 40. By this procedure a certainpercentage of hydrocarbons will be removed that would have'been revaporized and reintroduced into the mass of vapors if all of the reflux had been pumped into tower` 3 through spray 52. This is likewise true of the fractions vaporized in the steam stills 21 and 24 as by regulation of the heat and steam any desired amount may be distilledA olf and the residual products from the stills llO may be made to include any undesirable fractions that may enter them, these fractions may then be collected in the steam still residue tank 30 and heavy intermediate tank 46 and removed from the system to storage not shown, by means of pipes 31 and 47 controlled by valves 31 and 47.

The final condensation product also may be varied by regulating the cooling effect in the condensers 8 and 13 by varying tne amount of cooling medium circulated through the tubes 9 and 14.

By this combination of apparatus gieat 4 flexibility of operation is obtained together with very` close regulation ofthe resultant products. y

If crude oil is circulated through the condensers 8 and 13 it will absorb considerable heat from the vapors and if the crude is then passed to the still or stills quite an economy of` heat will'result in supplying heat of vaporization.

I have now described my invention in both process and apparatus so that one familiar with the art could construct and operate it.

What l claim as my invention is:

l. The process of fractionating hydrocarbons which comprises distilling the same and supplying fresh hydrocarbons to the still to replace the vaporized portions, partially condensing the vapors, passing the condensate to a separate still, redistilling a portion of the condensate and partially condensing the vapors by heat exchange with the fresh hydrocarbon supply to the still and finally condensing the residual vapors.

2. The process of producing hydrocarbons of predetermined boiling point range which comprises distilling the saine, and supplying fresh hydrocarbons to the still to replace the vaporized portions, scrubbing the va ors with hydrocarbons to remove the higher oiling point hydrocarbons, passing the residual vapors through a second partial condensing operation, removing and separately redistilling the first formed condensates and liquid wash hydrocarbons, and mixingvthe vapors therefrom with the uncondensed vapors of the first distillation, further partially con- (lensing the residual vapors by heat exchange with the fresh hydrocarbons supplied to replenish the still and finally condensing the residual vapors.

3. The process for the fractionation of hydrocarbons to produce therefrom hydrocarbons of predetermined boiling point range comprising distilling the same and supplying fresh hydrocarbons to take the place of those vaporized, partially condensing the primary vapors with scrubbing hydrocarbons, then further condensing them by lhea-t exchange with the ingoing fresh supply of hydrocarbons, then further partially condensing the remaining vapors, distilling the condensate and cooling the residue from said distillation and using it as the scrubbing hydrocarbon in the primary condensation step and finally condensing the residual' vapors.

4. The process for the fractionation .of hydrocarbonvaporstoproducetherefroinhydrocarbons of predetermined boiling point range consisting in distilling the same and supplying fresh hydrocarbons to take the place of those vaporized, partially condensing the vapors with a. scrubbing and vaporizable hydrocarbon, then further condensing the vapors by heat exchange with the ingoing fresh supply to the still, then further partially condensing the remaining vapors, distilling condensates and using the residue as the scrubbing agent in the primary condensing opration, and then condensing the residual vapors to produce the hydrocarbons of predetermined boiling point range.

5. An apparatus for the fractionation of hydrocarbons comprising a still, a fractionating tower, a second still for taking' condensates from the fractionating tower, a second fractionating tower, connections between the second fractionating tower and the first and also with the second mentioned still, a condenser in the upper part of the second tower, a pipe for conducting a supply of oil siy fill

to the rst mentioned still, said pipe conneeting with said condenser.

6. A process for the treatment of hydrocarbon vapors which comprises scrubbing the vapors with a liquid to separate out the higher boiling fractions, reetifying the uncondensed vapors, removing the scrubbing liquid, fractionating the scrubbing liquid to separate a liquid residual fraction from vaporized lower boiling fractions, passing the said separated vaporized lower boiling fractions into a second fractionating tower, therein condensing and separating an intermediate boiling fraction from a lower boiling vaporized fraction and recycling the intermediate fraction thus obtained to scrub the vapors to be treated.

7 A process for the treatment of hydrocarbon vapors which comprises kscrubbing the vapors with a liquid to separate out the higher boiling fractions, rectifying the uncondensed vapors, removing the scrubbing liquid, fractionating the scrubbing liquid, 1ntroducing a part of the scrubbing liquid into the vapors to be rectified, and recycling a liquid intermediate fraction of the scrubbing liquid to the vapors to be treated lto scrub the same.

8. A process for the treatment of hydrocarbons having the desired boiling characteristics which comprises forming a vapor deficient in certain constituents desired in the final condensate, scrubbing the vapors with a liquid having the desired. constituents, recti-fying the resultant vapors, fraction-ating the scrubbing liquid and separating a liquid residual fraction from vaporized lower boiling fractions, passing the said' separated vaporized lower boilingl fractions into a second' cient in certain constituents desired inthe final condensate, scrubbing the vapors with a liquid having the desired constituents, rectifying the resultant vapors, fractionating the scrubbing liquid, introducing a part of the scrubbing liquid into the vapors to be rectified, and recycling a liquid intermediate fraction of the scrubbing liquid to the vapors to be treated to scrub the same.

10. A process for the treatment of hydrocarbon vapors which comprises contacting said vapors with a liquid adapted to condense the heavy fractions of said vapors, rectifying the uncondensed vapors, withdrawing the condensed liquid fraction, fractionating said liquid fraction, combining a vaprous fraction formed on sald fractionation with said vapors undergoing rectification, forming a combined condensate from said vapors, and recycling said combined condensate to act as the first mentioned liquid to be contacted with vapors undergoing treatment.

11. A process for'the treatment of hydrocarbon vapors which comprises contacting said vapors with a liquid adapted to condense the heavy fractions of said vapors, rectifying the uncondensed vapors, withdrawing the condensed liquid fraction, fractionating said liquid fraction, rectifying a vaprous fraction formed from said fractionation to form a condensate, and recycling said condensate as said first mentioned liquid to be contacted with vapors undergoing fractionation.

12; A process for the treatment of hydrocarbon vapors which comprises contacting said vapors with a liquid adapted to condense the heavy fractions of said vapors, rectifying the uncondensed vapors, withdrawing the condensed liquid fraction, fractionating said liquid fraction, fractionatinga vaprous fraction resulting from said fractionation to form a residual condensate and a lighter overhead condensate, and recycling said residual condensate as said first mentioned liquid to be contacted with vapors undergoing treatment.

13. A process for the treatment of hydrocarbon vapors which comprises scrubbing the vapors with a liquid to separate out the higher boiling fractions, rectifying the uncondensed vapors, removing the scrubbing liquid, fractionating the scrubbing liquid and separating a liquid residual fraction from vaporized lower boiling fractions, passing the said separated vaporized lower boiling v fractions into a second fractionating tower, therein condensing and separating an intermediate boiling fraction from a lower boiling vaporized fraction, recycling the intermediate fraction thus obtained to scrub the vapors to be treated, and addin to the recycling liquid a supply of scrubbing liquid from an external source.

14. A process for the treatment of hydrocarbon vapors which comprises scrubbing the vapors with a liquid to separate out the higher boiling fractions, rectifying the uncondensed vapors, removing the scrubbing liquid, fractionating the scrubbing liquid, introducing a part of the scrubbing liquid into the vapors to be rectified, recycling a liquid intermediate fraction of the scrubbing liquid to the vapors to be treated to scrub the same, and adding to the liquid which is circulated to be contacted with the vapors an additional supply of liquid from an external source.

15. A process for the production of hydrocarbons having a desired boiling characteristic which comprises forming a vapor deficient in certain constituents desired in the final condensate, scrubbing the vapors with a liquid having the desired constituents, rectifying the resultant vapors, "fractionating the scrubbing liquid and separating a liquid residual fraction from vaporized lower boiling fractions, passing the said separated vaporized lower boiling fractions into a second fractionating tower, therein condensing and separating an intermediate boiling fraction from. a lower boiling vaporized fraction,recycling the intermediate fraction thus obtained to scrub the vapors to be treated and adding to the recycling liquid a scrubbing liquid from an external source. q

16. A process for the production of hydrocarbons having a desired boiling characteristic which comprises forming a vapor deficient in certain constituents desired in the final condensate, scrubbing the lvapors with a liquid having the desired constituents, rectifying the resultantvapors, fractionating the scrubbing liquid, introducing apart of the scrubbing liquid into the vapors to be rectified, recycling a liquid intermediate fraction of the scrubbing liquid to the vapors to be treatedto scrub the same, and adding to the liquid which is circulated to be contacted with the vapors an additional supply of liquid from an external source. i

17. A processfor the treatment of hydrocarbon vapors which comprises contacting said vapors with a liquid adapted to condense the heavy fractions of said vapors, rectifying the uncondensed vapors, withdrawing the condensed liquid fraction, fractionating said liquid fraction, combining a vaprous fraction formed on said fractionations with said vapors undergoing rectification, forming a combined condensate from said vapors, recycling said combined condensate to act as the first mentioned liquid to be contacted with vapors undergoing treatment, and adding to the liquid which is circulated to be contacted with the vapors an additional supply of liquid from an external source.

18. A process for the treatment of hydrocarbon vapors which comprises contacting said vapors with a liquid adapted to condense the heavy fractions of said vapors, rectifying the uncondensed vapors, withdrawing the condensed liquid fraction, fractionating said liquid fraction, rectifying a vaprous fraction formed from said fractionations to iorm a condensate, recycling said condensate as first I mentioned liquid to be contacted with vapors undergoing fractionation, and adding to the liquid which is circulated to be contacted with the vapors an additional supply of liquid from an external source.

19. A process for the treatment of hydrocarbon vapors which comprises contacting said vapors with a liquid adapted to condense the heavy fractions of said vapors, rectify-v ing the uncondensed vapors, withdrawing the condensed liquid fraction, fractionating said liquid fraction, ractionating avaprous fraction resulting from said fractionation to form a residual condensate and a lighter overhead condensate, recycling said residual condensate as said lirst mentioned liquid to be contacted-with vapors undergoing treatment, and adding to the liquid whichis circulated to be contacted with the vapors an additional supply of liquid from an external source.

Q0. An apparatus for the separation of hydrocarbon vapors comprising fractionating towers, connected in series, means for passing vapors from one tower to the other, means for withdrawing liquid Jfrom said towers, means'for distilling said withdrawn liquid, means for conducting vapors of an intermediate boiling range from said distilling means, and means for introducing said vapors into the first of said fractionating towers.

In testimony whereof l hereunto aiiix my signature.

JOHN C. BLACK. 

